Previous work in this laboratory has suggested that the frontal eye fields of the cerebral cortex contain a mechanism for the guidance of saccadic eye movements. There are neurons which discharge in response to the stimulus evoking a saccade, and others which dishcharge before purposive eye movements. To study the quantitative aspects of this system, single cell recordings were made in the frontal eye fields of rhesus monkeys performing visually guided eye movements. Quantitative analysis of receptive and movement fields of single neurons have revealed a consistent pattern for visual and movement activities in the frontal eye fields. Both types of cells are tuned differently for amplitude and direction of saccade. Direction tuning follows a simple normal Gaussian distribution. Amplitude tuning follows a more complicated log Gaussian distribution. The amplitude and direction of the eye movement evoked by electrical stimulation are predicted by the quantitative nature of the movement fields of the neurons found at the site of stimulation.